1. Field of the Invention
This invention relates to scanning optical systems, and particularly to a scanning optical system with less distortion (aberration).
2. Description of the Prior Art
A scanning optical system is well known in which in a laser printer or the like, a laser beam is deflected by a rotary polyhedral mirror or the like and focusing and scanning are effected on a scanning surface by an f.theta. lens. For example, Japanese Patent Application Laid-Open Nos. 5706/83 and 93021/83 disclose a simple scanning optical system which uses a single f.theta. lens. This scanning optical system has no problem when it is used for releasing characters but poses a problem of distortion due to distortion aberration when the system is used for releasing drawings. If this distortion is compensated for, the curvature of an image surface has to be sacrificed, as described in detail in the aforesaid applications.